What could be more contradictory, more disingenuous or just plain fishier than a film that sets out to promote the virtues of reading? Even an admiring adaptation of a literary classic is an odd mixture of a homage and a desecration, so what hope is there of a routine Hollywood venture? Yet two of this week's releases, The Pagemaster and The Neverending Story III show troubled youngsters healing themselves and learning about the world as a result of what they find in a library.

There is an element of bad faith in both films, a sort of strident wholesomeness that says, for the benefit of parents, "we're pro-family, we're pro-education, we care about children and the future", while continuing to offer a younger audience plenty ofstandard chases and ordinary special effects. (The Neverending Story III can at least claim to be derived from a book, and has roots that antedate the recent controversies.) But there is also an almost poignant confusion in both films about the actual workings of fantasy - how imaginary lives take us away from our own but also somehow return us to them - and even more so about what we demand of children.

Richard (Macaulay Culkin), the hero of The Pagemaster, is an unusually phobic young boy, frightened even to climb the ladder up to the treehouse his loving father has built for him.

He recites accident statistics in defence of his many phobias like a junior version of Dustin Hoffman in Rain Man justifying his fear of flying. When Richard ventures out of the house, his bicycle is so heavily defended it's like a two-wheeled tank. But then he hides out from a rainstorm in a public library, falls and bangs his head, and enters an animated world where there is always some threatening situation between him and the Exit sign he so desperately wants to reach.

There are some decent jokes for adult viewers (the librarian is called Dewey, in homage to the inventor of the celebrated classification system) and a nice plot conceit: Richard is assisted by three books representing the genres of Adventure, Horror and Fantasy (an odd mixture, Fantasy, voiced by Whoopi Goldberg at her cutest but modelled facially more on Angela Lansbury). They help him not out of disinterested virtue but because they see his library card as their ticket to freedom.

Along the way to the Exit sign Richard learns to overcome his fears, even if the film seems rather vague about how this actually comes about. The librarian, transformed into a guide called the Pagemaster, encourages him with two slogans that seem to havequite different implications: Trust the books and Reach deep within yourself, and seize the courage.

"I'm a cartoon!" exclaims Richard after his transformation, until the Pagemaster, guardian of the written word, corrects him gravely: "You are an illustration." Perhaps the Pagemaster is protesting too much, since he himself is a film or actually an animation reference, being modelled on the Sorcerer from Fantasia (James Horner's music score has already paraphrased The Sorcerer's Apprentice). The self-appointed defender of written culture turns out to be a distant by-blow of Walt Disney.

But then the strained detente between film and books in The Pagemaster may actually be a defensive alliance against a common enemy too dreadful to be mentioned: interactive video. Certainly Richard's world before it is filled by books is bizarrely empty of other activities, though logically a fearful child would be likely to find compensation in the artificial challenges of Game Boy or Nintendo.

Even if the makers of The Pagemaster (David Kirschner, writer and producer, clearly the guiding light) are sincere in their belief that books are the real virtual reality, they have some way to go before they can make their case in cinematic terms. Maybe30 seconds of animation can hope to convey the wonders of Moby Dick to a child - but not this 30 seconds.

For some years now, Disney cartoons have been careful to include at least one sequence of vertiginous computerised perspectives that beat video arcades at their own game, but The Pagemaster's most effective single effect has a curiously nostalgic, Fantasia timbre: a dance of the fireflies where the insects are rendered as little winged dancers, their bodies defined by flickering filaments of lightning.

In The Neverending Story III Fantasia is the name not of a classic animated film but of a parallel world of magical creatures - gnomes, walking trees, dragons and such - to which the hero Bastian (Jason James Richter) can transport himself, with the helpof a miraculously interactive book called The Neverending Story, when his personal reality becomes too much to bear. His father has remarried, and Bastian's new stepmother, though neurotically eager to win him over (a pleasing performance from Tracey Ellis) has a daughter of her own who is definitely hostile. Bastian also has to cope with a new school where the Nasties, a gang of illiterate dropouts-in-the-making, single him out for bullying.

The overall conception of the film is very much on the sweet side (story by Karin Howard, using characters from Michael Ende's original novel) but screenwriter Jeff Lieberman has come up with some unexpectedly astringent dialogue. The Neverending Story III also shows itself rather more sophisticated than The Pagemaster in the suggestion that reality and fantasy are not only individually fragile, but precariously interdependent.

More confusing is the way the two realms run together in the dialogue before they are scheduled to meet in the story. The inhabitants of Fantasia are slightly tatty animatronics, seemingly from the bargain basement of Jim Henson's Creature Shop, including a flying furry dragon who is mostly spaniel, a family of giant stone people and a Bark Troll, a walking, wisecracking tree. The Bark Troll is transported to Earth in a wishing accident and professes astonishment at the strangeness of terrestrial ways - but all his references are, by arboreal standards, oddly hip and worldly. Coming across a logging camp, he refers to a chainsaw massacre; on Halloween, he accuses someone of getting their costume from K-Mart.

The assumption seems to be that kids will marvel at the visuals, their parents will tune into the dialogue, but no-one will do both. Even so, there's a jarring sub-Flintstone sequence where the father of the stone family sets off on his bicycle to get food while singing the dubious 1960s classic "Born to Be Wild". If you can get MTV on Fantasia, is it really a world worth saving?

It may not be strictly true to say that in The Neverending Story III the devil gets the best tunes, but the Nasties certainly have the better rhythm section. Fantasia can only boast nostalgic rock and reverential orchestral noodlings, while at least the illiterates have drum machines and a decent beat.

The strangest thing about the Nasties is that they are startlingly old to be at high school. A claim that they're going for the record in terms of school years held back, doesn't quite cover the age gap between Bastian and the baddies (Jack Black's unnecessarily charismatic Slip, played as a sort of stubbled biker skinhead, wouldn't look out of place in Romper Stomper).

It begins to look, in fact, as if the film's real preoccupation is not with reading, but sexuality. Bastian and the Nasties are on opposite sides of the chasm of puberty, and the screenplay wants to keep it that way. The space which the love interest would occupy in most films is filled instead by the tense relationship between Bastian and his stepsister Nicole (Melody Kay). When they express physical affection towards each other at the end of the film, it is a sign not of romance but of a family reconstituted against the odds.

Nicole proves her pre-adolescent status in an undignified sequence in which, having stolen the magical stone that binds the realms together and grants all wishes to the holder, she can think of nothing better to do than go shopping. The love of booklearning which The Neverending Story III shares with The Pagemaster turns out to be rather a deceptive thing. The fear of a lapse in education stands in for a different loss, the necessary loss of innocence, and the enemy is not illiteracy but sexual knowledge, which parents can't really hope to drown in books.